Snare instruments are electrosurgical devices that are primarily used for removing small growths from the lining of internal body cavities (e.g., polyps within the bowels), such as during polypectomy procedures. These snares include a wire loop configured to encircle the small growth, and then electrosurgical energy is applied to the tissue to cut and/or coagulate. Generally, snare instruments include an elongate tubular member having a handle, such as a sheath, a shaft extending through the tubular member having a wire loop connected to the distal end (“distal” refers to that portion that is further from the user, while “proximal” refers to that portion that is closer to the user or surgeon) thereof. The loop is opened by pushing the shaft toward the distal end thereby moving/extracting the loop outside the tubular member and is closed by pulling the shaft toward the proximal end thereby moving/retracting the loop inside the tubular member.
The snare instrument is generally inserted into internal body cavities through an endoscope. In the case of a polypectomy, the instrument is inserted through the gastrointestinal tract and moved toward the polyp(s) marked for removal. During insertion, the loop is retracted into the shaft, and once at the removal site, it is extracted and is expanded around the polyp. The surgeon then constricts the loop around the polyp and electrosurgical energy is applied thereto.
Currently, snare instruments are used without providing any sensory feedback to the generator. The surgeon has to manually adjust the energy delivered to the snare while simultaneously adjusting the pressure exacted on the polyp by the loop. For instance, as the surgeon increases the pressure, the energy must also increase so that the energy increases proportionally with pressure. The contiguous increase in pressure and energy allows for the polyp to be removed only after the stalk portion thereof has been cauterized. Increasing energy too slowly may detrimentally affect removal of the polyp causing bleeding. Increasing energy too rapidly may result in damage to the surrounding tissue. Presently, the success of these surgical procedures depended on the experience of the surgeon to control the pressure and energy delivered to the snare instrument. Such manual control of these operating factors is not infallible.